On Fri, May 11, 2012 at 01:32:34PM -0700, Andrew Morton wrote: > On Fri, 11 May 2012 23:02:13 +0300 > Sami Liedes <sami.liedes@xxxxxx> wrote: > > > On Fri, May 11, 2012 at 12:59:21PM -0700, Andrew Morton wrote: > > > > [67031.755786] BUG: Bad page state in process wcg_gfam_6.11_i pfn:02519 > > > > [67031.755790] page:ffffea0000094640 count:0 mapcount:0 mapping: > > > > (null) index:0x7f1eb293b > > > > [67031.755792] page flags: 0x4000000000000014(referenced|dirty) > > > > > > AFAICT we got this warning because the page allocator found a free page > > > with PG_referenced and PG_dirty set. > > > > > > It would be a heck of a lot more useful if we'd been told about this > > > when the page was freed, not when it was reused! Can anyone think of a > > > reason why PAGE_FLAGS_CHECK_AT_FREE doesn't include these flags (at > > > least)? > > > > Would it be useful if I tried to reproduce this with some debugging > > options turned on, for example CONFIG_DEBUG_VM? > > > > Sure, thanks, that might turn something up. > Documentation/SubmitChecklist recommends > > : 12: Has been tested with CONFIG_PREEMPT, CONFIG_DEBUG_PREEMPT, > : CONFIG_DEBUG_SLAB, CONFIG_DEBUG_PAGEALLOC, CONFIG_DEBUG_MUTEXES, > : CONFIG_DEBUG_SPINLOCK, CONFIG_DEBUG_ATOMIC_SLEEP, CONFIG_PROVE_RCU > : and CONFIG_DEBUG_OBJECTS_RCU_HEAD all simultaneously enabled. > > although that list might be a bit out of date; it certainly should > include CONFIG_DEBUG_VM! FWIW, that Fedora report of this had DEBUG_VM enabled, and it doesn't seem that there was any earlier oops/warn judging by the lack of tainting. Dave -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>